Your inboat speakers will handle 125 watts rms. That head unit is going to put out 18 watts rms to each speaker. I'd say you be wasting having a nice Exile inboat speaker if your going to run it off the HU .02. Do you have 2 pairs of inboats? Or just 1 pair? How loud are you wanting to get with the sub? Ported or sealed? The ideal location would probably be under the helm, if you have room. Does everything have to be brand new equipment? I got on craigslist and searched for a nice sub and amp to put in my boat, and I wanted to go as loud as I can get for 1 sub. I found a 13w7 JL sub and a 1000/1 JL slash amp, for like 4-500 bucks, which is a pretty sweet deal. A few pics of the interior might help people give you a good location to fit the sub based on where the most space is. You'll definitely have to get another amp, IMO.

I could if he was interested. I considered putting it in my company vehicle (already have an App Radio 1 in there) as it wouldn't cost me anything to do it...but if he is interested I'd consider selling it I suppose. I guess I really don't "need" a sub in my work vehicle.